/*
 * QR Code generator library (C++)
 *
 * Copyright (c) Project Nayuki. (MIT License)
 * https://www.nayuki.io/page/qr-code-generator-library
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 * - The above copyright notice and this permission notice shall be included in
 *   all copies or substantial portions of the Software.
 * - The Software is provided "as is", without warranty of any kind, express or
 *   implied, including but not limited to the warranties of merchantability,
 *   fitness for a particular purpose and noninfringement. In no event shall the
 *   authors or copyright holders be liable for any claim, damages or other
 *   liability, whether in an action of contract, tort or otherwise, arising from,
 *   out of or in connection with the Software or the use or other dealings in the
 *   Software.
 */

#include "qrcodegen.h"

#include <algorithm>
#include <cassert>
#include <climits>
#include <cstddef>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <utility>

using std::int8_t;
using std::size_t;
using std::uint8_t;
using std::vector;

namespace qrcodegen {

/*---- Class QrSegment ----*/

QrSegment::Mode::Mode(int mode, int cc0, int cc1, int cc2) : modeBits(mode) {
  numBitsCharCount[0] = cc0;
  numBitsCharCount[1] = cc1;
  numBitsCharCount[2] = cc2;
}

int QrSegment::Mode::getModeBits() const {
  return modeBits;
}

int QrSegment::Mode::numCharCountBits(int ver) const {
  return numBitsCharCount[(ver + 7) / 17];
}

const QrSegment::Mode QrSegment::Mode::NUMERIC(0x1, 10, 12, 14);
const QrSegment::Mode QrSegment::Mode::ALPHANUMERIC(0x2, 9, 11, 13);
const QrSegment::Mode QrSegment::Mode::BYTE(0x4, 8, 16, 16);
const QrSegment::Mode QrSegment::Mode::KANJI(0x8, 8, 10, 12);
const QrSegment::Mode QrSegment::Mode::ECI(0x7, 0, 0, 0);

QrSegment QrSegment::makeBytes(const vector<uint8_t> &data) {
  if (data.size() > static_cast<unsigned int>(INT_MAX))
    throw std::length_error("Data too long");
  BitBuffer bb;
  for (uint8_t b : data)
    bb.appendBits(b, 8);
  return QrSegment(Mode::BYTE, static_cast<int>(data.size()), std::move(bb));
}

QrSegment QrSegment::makeNumeric(const char *digits) {
  BitBuffer bb;
  int accumData = 0;
  int accumCount = 0;
  int charCount = 0;
  for (; *digits != '\0'; digits++, charCount++) {
    char c = *digits;
    if (c < '0' || c > '9')
      throw std::domain_error("String contains non-numeric characters");
    accumData = accumData * 10 + (c - '0');
    accumCount++;
    if (accumCount == 3) {
      bb.appendBits(static_cast<uint32_t>(accumData), 10);
      accumData = 0;
      accumCount = 0;
    }
  }
  if (accumCount > 0)  // 1 or 2 digits remaining
    bb.appendBits(static_cast<uint32_t>(accumData), accumCount * 3 + 1);
  return QrSegment(Mode::NUMERIC, charCount, std::move(bb));
}

QrSegment QrSegment::makeAlphanumeric(const char *text) {
  BitBuffer bb;
  int accumData = 0;
  int accumCount = 0;
  int charCount = 0;
  for (; *text != '\0'; text++, charCount++) {
    const char *temp = std::strchr(ALPHANUMERIC_CHARSET, *text);
    if (temp == nullptr)
      throw std::domain_error("String contains unencodable characters in alphanumeric mode");
    accumData = accumData * 45 + static_cast<int>(temp - ALPHANUMERIC_CHARSET);
    accumCount++;
    if (accumCount == 2) {
      bb.appendBits(static_cast<uint32_t>(accumData), 11);
      accumData = 0;
      accumCount = 0;
    }
  }
  if (accumCount > 0)  // 1 character remaining
    bb.appendBits(static_cast<uint32_t>(accumData), 6);
  return QrSegment(Mode::ALPHANUMERIC, charCount, std::move(bb));
}

vector<QrSegment> QrSegment::makeSegments(const char *text) {
  // Select the most efficient segment encoding automatically
  vector<QrSegment> result;
  if (*text == '\0')
    ;  // Leave result empty
  else if (isNumeric(text))
    result.push_back(makeNumeric(text));
  else if (isAlphanumeric(text))
    result.push_back(makeAlphanumeric(text));
  else {
    vector<uint8_t> bytes;
    for (; *text != '\0'; text++)
      bytes.push_back(static_cast<uint8_t>(*text));
    result.push_back(makeBytes(bytes));
  }
  return result;
}

QrSegment QrSegment::makeEci(long assignVal) {
  BitBuffer bb;
  if (assignVal < 0)
    throw std::domain_error("ECI assignment value out of range");
  else if (assignVal < (1 << 7))
    bb.appendBits(static_cast<uint32_t>(assignVal), 8);
  else if (assignVal < (1 << 14)) {
    bb.appendBits(2, 2);
    bb.appendBits(static_cast<uint32_t>(assignVal), 14);
  } else if (assignVal < 1000000L) {
    bb.appendBits(6, 3);
    bb.appendBits(static_cast<uint32_t>(assignVal), 21);
  } else
    throw std::domain_error("ECI assignment value out of range");
  return QrSegment(Mode::ECI, 0, std::move(bb));
}

QrSegment::QrSegment(const Mode &md, int numCh, const std::vector<bool> &dt)
  : mode(&md),
    numChars(numCh),
    data(dt) {
  if (numCh < 0)
    throw std::domain_error("Invalid value");
}

QrSegment::QrSegment(const Mode &md, int numCh, std::vector<bool> &&dt)
  : mode(&md),
    numChars(numCh),
    data(std::move(dt)) {
  if (numCh < 0)
    throw std::domain_error("Invalid value");
}

int QrSegment::getTotalBits(const vector<QrSegment> &segs, int version) {
  int result = 0;
  for (const QrSegment &seg : segs) {
    int ccbits = seg.mode->numCharCountBits(version);
    if (seg.numChars >= (1L << ccbits))
      return -1;  // The segment's length doesn't fit the field's bit width
    if (4 + ccbits > INT_MAX - result)
      return -1;  // The sum will overflow an int type
    result += 4 + ccbits;
    if (seg.data.size() > static_cast<unsigned int>(INT_MAX - result))
      return -1;  // The sum will overflow an int type
    result += static_cast<int>(seg.data.size());
  }
  return result;
}

bool QrSegment::isNumeric(const char *text) {
  for (; *text != '\0'; text++) {
    char c = *text;
    if (c < '0' || c > '9')
      return false;
  }
  return true;
}

bool QrSegment::isAlphanumeric(const char *text) {
  for (; *text != '\0'; text++) {
    if (std::strchr(ALPHANUMERIC_CHARSET, *text) == nullptr)
      return false;
  }
  return true;
}

const QrSegment::Mode &QrSegment::getMode() const {
  return *mode;
}

int QrSegment::getNumChars() const {
  return numChars;
}

const std::vector<bool> &QrSegment::getData() const {
  return data;
}

const char *QrSegment::ALPHANUMERIC_CHARSET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:";

/*---- Class QrCode ----*/

int QrCode::getFormatBits(Ecc ecl) {
  switch (ecl) {
  case Ecc::LOW:
    return 1;
  case Ecc::MEDIUM:
    return 0;
  case Ecc::QUARTILE:
    return 3;
  case Ecc::HIGH:
    return 2;
  default:
    throw std::logic_error("Unreachable");
  }
}

QrCode QrCode::encodeText(const char *text, Ecc ecl) {
  vector<QrSegment> segs = QrSegment::makeSegments(text);
  return encodeSegments(segs, ecl);
}

QrCode QrCode::encodeBinary(const vector<uint8_t> &data, Ecc ecl) {
  vector<QrSegment> segs{QrSegment::makeBytes(data)};
  return encodeSegments(segs, ecl);
}

QrCode QrCode::encodeSegments(const vector<QrSegment> &segs, Ecc ecl, int minVersion,
                              int maxVersion, int mask, bool boostEcl) {
  if (!(MIN_VERSION <= minVersion && minVersion <= maxVersion && maxVersion <= MAX_VERSION)
      || mask < -1 || mask > 7)
    throw std::invalid_argument("Invalid value");

  // Find the minimal version number to use
  int version, dataUsedBits;
  for (version = minVersion;; version++) {
    int dataCapacityBits = getNumDataCodewords(version, ecl) * 8;  // Number of data bits available
    dataUsedBits = QrSegment::getTotalBits(segs, version);
    if (dataUsedBits != -1 && dataUsedBits <= dataCapacityBits)
      break;                      // This version number is found to be suitable
    if (version >= maxVersion) {  // All versions in the range could not fit the given data
      std::ostringstream sb;
      if (dataUsedBits == -1)
        sb << "Segment too long";
      else {
        sb << "Data length = " << dataUsedBits << " bits, ";
        sb << "Max capacity = " << dataCapacityBits << " bits";
      }
      throw data_too_long(sb.str());
    }
  }
  assert(dataUsedBits != -1);

  // Increase the error correction level while the data still fits in the current version number
  for (Ecc newEcl : {Ecc::MEDIUM, Ecc::QUARTILE, Ecc::HIGH}) {  // From low to high
    if (boostEcl && dataUsedBits <= getNumDataCodewords(version, newEcl) * 8)
      ecl = newEcl;
  }

  // Concatenate all segments to create the data bit string
  BitBuffer bb;
  for (const QrSegment &seg : segs) {
    bb.appendBits(static_cast<uint32_t>(seg.getMode().getModeBits()), 4);
    bb.appendBits(static_cast<uint32_t>(seg.getNumChars()),
                  seg.getMode().numCharCountBits(version));
    bb.insert(bb.end(), seg.getData().begin(), seg.getData().end());
  }
  assert(bb.size() == static_cast<unsigned int>(dataUsedBits));

  // Add terminator and pad up to a byte if applicable
  size_t dataCapacityBits = static_cast<size_t>(getNumDataCodewords(version, ecl)) * 8;
  assert(bb.size() <= dataCapacityBits);
  bb.appendBits(0, std::min(4, static_cast<int>(dataCapacityBits - bb.size())));
  bb.appendBits(0, (8 - static_cast<int>(bb.size() % 8)) % 8);
  assert(bb.size() % 8 == 0);

  // Pad with alternating bytes until data capacity is reached
  for (uint8_t padByte = 0xEC; bb.size() < dataCapacityBits; padByte ^= 0xEC ^ 0x11)
    bb.appendBits(padByte, 8);

  // Pack bits into bytes in big endian
  vector<uint8_t> dataCodewords(bb.size() / 8);
  for (size_t i = 0; i < bb.size(); i++)
    dataCodewords.at(i >> 3) |= (bb.at(i) ? 1 : 0) << (7 - (i & 7));

  // Create the QR Code object
  return QrCode(version, ecl, dataCodewords, mask);
}

QrCode::QrCode(int ver, Ecc ecl, const vector<uint8_t> &dataCodewords, int msk)
  :  // Initialize fields and check arguments
    version(ver),
    errorCorrectionLevel(ecl) {
  if (ver < MIN_VERSION || ver > MAX_VERSION)
    throw std::domain_error("Version value out of range");
  if (msk < -1 || msk > 7)
    throw std::domain_error("Mask value out of range");
  size = ver * 4 + 17;
  size_t sz = static_cast<size_t>(size);
  modules = vector<vector<bool>>(sz, vector<bool>(sz));  // Initially all light
  isFunction = vector<vector<bool>>(sz, vector<bool>(sz));

  // Compute ECC, draw modules
  drawFunctionPatterns();
  const vector<uint8_t> allCodewords = addEccAndInterleave(dataCodewords);
  drawCodewords(allCodewords);

  // Do masking
  if (msk == -1) {  // Automatically choose best mask
    long minPenalty = LONG_MAX;
    for (int i = 0; i < 8; i++) {
      applyMask(i);
      drawFormatBits(i);
      long penalty = getPenaltyScore();
      if (penalty < minPenalty) {
        msk = i;
        minPenalty = penalty;
      }
      applyMask(i);  // Undoes the mask due to XOR
    }
  }
  assert(0 <= msk && msk <= 7);
  mask = msk;
  applyMask(msk);       // Apply the final choice of mask
  drawFormatBits(msk);  // Overwrite old format bits

  isFunction.clear();
  isFunction.shrink_to_fit();
}

int QrCode::getVersion() const {
  return version;
}

int QrCode::getSize() const {
  return size;
}

QrCode::Ecc QrCode::getErrorCorrectionLevel() const {
  return errorCorrectionLevel;
}

int QrCode::getMask() const {
  return mask;
}

bool QrCode::getModule(int x, int y) const {
  return 0 <= x && x < size && 0 <= y && y < size && module(x, y);
}

void QrCode::drawFunctionPatterns() {
  // Draw horizontal and vertical timing patterns
  for (int i = 0; i < size; i++) {
    setFunctionModule(6, i, i % 2 == 0);
    setFunctionModule(i, 6, i % 2 == 0);
  }

  // Draw 3 finder patterns (all corners except bottom right; overwrites some timing modules)
  drawFinderPattern(3, 3);
  drawFinderPattern(size - 4, 3);
  drawFinderPattern(3, size - 4);

  // Draw numerous alignment patterns
  const vector<int> alignPatPos = getAlignmentPatternPositions();
  size_t numAlign = alignPatPos.size();
  for (size_t i = 0; i < numAlign; i++) {
    for (size_t j = 0; j < numAlign; j++) {
      // Don't draw on the three finder corners
      if (!((i == 0 && j == 0) || (i == 0 && j == numAlign - 1) || (i == numAlign - 1 && j == 0)))
        drawAlignmentPattern(alignPatPos.at(i), alignPatPos.at(j));
    }
  }

  // Draw configuration data
  drawFormatBits(0);  // Dummy mask value; overwritten later in the constructor
  drawVersion();
}

void QrCode::drawFormatBits(int msk) {
  // Calculate error correction code and pack bits
  int data = getFormatBits(errorCorrectionLevel) << 3 | msk;  // errCorrLvl is uint2, msk is uint3
  int rem = data;
  for (int i = 0; i < 10; i++)
    rem = (rem << 1) ^ ((rem >> 9) * 0x537);
  int bits = (data << 10 | rem) ^ 0x5412;  // uint15
  assert(bits >> 15 == 0);

  // Draw first copy
  for (int i = 0; i <= 5; i++)
    setFunctionModule(8, i, getBit(bits, i));
  setFunctionModule(8, 7, getBit(bits, 6));
  setFunctionModule(8, 8, getBit(bits, 7));
  setFunctionModule(7, 8, getBit(bits, 8));
  for (int i = 9; i < 15; i++)
    setFunctionModule(14 - i, 8, getBit(bits, i));

  // Draw second copy
  for (int i = 0; i < 8; i++)
    setFunctionModule(size - 1 - i, 8, getBit(bits, i));
  for (int i = 8; i < 15; i++)
    setFunctionModule(8, size - 15 + i, getBit(bits, i));
  setFunctionModule(8, size - 8, true);  // Always dark
}

void QrCode::drawVersion() {
  if (version < 7)
    return;

  // Calculate error correction code and pack bits
  int rem = version;  // version is uint6, in the range [7, 40]
  for (int i = 0; i < 12; i++)
    rem = (rem << 1) ^ ((rem >> 11) * 0x1F25);
  long bits = static_cast<long>(version) << 12 | rem;  // uint18
  assert(bits >> 18 == 0);

  // Draw two copies
  for (int i = 0; i < 18; i++) {
    bool bit = getBit(bits, i);
    int a = size - 11 + i % 3;
    int b = i / 3;
    setFunctionModule(a, b, bit);
    setFunctionModule(b, a, bit);
  }
}

void QrCode::drawFinderPattern(int x, int y) {
  for (int dy = -4; dy <= 4; dy++) {
    for (int dx = -4; dx <= 4; dx++) {
      int dist = std::max(std::abs(dx), std::abs(dy));  // Chebyshev/infinity norm
      int xx = x + dx, yy = y + dy;
      if (0 <= xx && xx < size && 0 <= yy && yy < size)
        setFunctionModule(xx, yy, dist != 2 && dist != 4);
    }
  }
}

void QrCode::drawAlignmentPattern(int x, int y) {
  for (int dy = -2; dy <= 2; dy++) {
    for (int dx = -2; dx <= 2; dx++)
      setFunctionModule(x + dx, y + dy, std::max(std::abs(dx), std::abs(dy)) != 1);
  }
}

void QrCode::setFunctionModule(int x, int y, bool isDark) {
  size_t ux = static_cast<size_t>(x);
  size_t uy = static_cast<size_t>(y);
  modules.at(uy).at(ux) = isDark;
  isFunction.at(uy).at(ux) = true;
}

bool QrCode::module(int x, int y) const {
  return modules.at(static_cast<size_t>(y)).at(static_cast<size_t>(x));
}

vector<uint8_t> QrCode::addEccAndInterleave(const vector<uint8_t> &data) const {
  if (data.size() != static_cast<unsigned int>(getNumDataCodewords(version, errorCorrectionLevel)))
    throw std::invalid_argument("Invalid argument");

  // Calculate parameter numbers
  int numBlocks = NUM_ERROR_CORRECTION_BLOCKS[static_cast<int>(errorCorrectionLevel)][version];
  int blockEccLen = ECC_CODEWORDS_PER_BLOCK[static_cast<int>(errorCorrectionLevel)][version];
  int rawCodewords = getNumRawDataModules(version) / 8;
  int numShortBlocks = numBlocks - rawCodewords % numBlocks;
  int shortBlockLen = rawCodewords / numBlocks;

  // Split data into blocks and append ECC to each block
  vector<vector<uint8_t>> blocks;
  const vector<uint8_t> rsDiv = reedSolomonComputeDivisor(blockEccLen);
  for (int i = 0, k = 0; i < numBlocks; i++) {
    vector<uint8_t> dat(data.cbegin() + k,
                        data.cbegin()
                          + (k + shortBlockLen - blockEccLen + (i < numShortBlocks ? 0 : 1)));
    k += static_cast<int>(dat.size());
    const vector<uint8_t> ecc = reedSolomonComputeRemainder(dat, rsDiv);
    if (i < numShortBlocks)
      dat.push_back(0);
    dat.insert(dat.end(), ecc.cbegin(), ecc.cend());
    blocks.push_back(std::move(dat));
  }

  // Interleave (not concatenate) the bytes from every block into a single sequence
  vector<uint8_t> result;
  for (size_t i = 0; i < blocks.at(0).size(); i++) {
    for (size_t j = 0; j < blocks.size(); j++) {
      // Skip the padding byte in short blocks
      if (i != static_cast<unsigned int>(shortBlockLen - blockEccLen)
          || j >= static_cast<unsigned int>(numShortBlocks))
        result.push_back(blocks.at(j).at(i));
    }
  }
  assert(result.size() == static_cast<unsigned int>(rawCodewords));
  return result;
}

void QrCode::drawCodewords(const vector<uint8_t> &data) {
  if (data.size() != static_cast<unsigned int>(getNumRawDataModules(version) / 8))
    throw std::invalid_argument("Invalid argument");

  size_t i = 0;  // Bit index into the data
  // Do the funny zigzag scan
  for (int right = size - 1; right >= 1; right -= 2) {  // Index of right column in each column pair
    if (right == 6)
      right = 5;
    for (int vert = 0; vert < size; vert++) {  // Vertical counter
      for (int j = 0; j < 2; j++) {
        size_t x = static_cast<size_t>(right - j);  // Actual x coordinate
        bool upward = ((right + 1) & 2) == 0;
        size_t y = static_cast<size_t>(upward ? size - 1 - vert : vert);  // Actual y coordinate
        if (!isFunction.at(y).at(x) && i < data.size() * 8) {
          modules.at(y).at(x) = getBit(data.at(i >> 3), 7 - static_cast<int>(i & 7));
          i++;
        }
        // If this QR Code has any remainder bits (0 to 7), they were assigned as
        // 0/false/light by the constructor and are left unchanged by this method
      }
    }
  }
  assert(i == data.size() * 8);
}

void QrCode::applyMask(int msk) {
  if (msk < 0 || msk > 7)
    throw std::domain_error("Mask value out of range");
  size_t sz = static_cast<size_t>(size);
  for (size_t y = 0; y < sz; y++) {
    for (size_t x = 0; x < sz; x++) {
      bool invert;
      switch (msk) {
      case 0:
        invert = (x + y) % 2 == 0;
        break;
      case 1:
        invert = y % 2 == 0;
        break;
      case 2:
        invert = x % 3 == 0;
        break;
      case 3:
        invert = (x + y) % 3 == 0;
        break;
      case 4:
        invert = (x / 3 + y / 2) % 2 == 0;
        break;
      case 5:
        invert = x * y % 2 + x * y % 3 == 0;
        break;
      case 6:
        invert = (x * y % 2 + x * y % 3) % 2 == 0;
        break;
      case 7:
        invert = ((x + y) % 2 + x * y % 3) % 2 == 0;
        break;
      default:
        throw std::logic_error("Unreachable");
      }
      modules.at(y).at(x) = modules.at(y).at(x) ^ (invert & !isFunction.at(y).at(x));
    }
  }
}

long QrCode::getPenaltyScore() const {
  long result = 0;

  // Adjacent modules in row having same color, and finder-like patterns
  for (int y = 0; y < size; y++) {
    bool runColor = false;
    int runX = 0;
    std::array<int, 7> runHistory = {};
    for (int x = 0; x < size; x++) {
      if (module(x, y) == runColor) {
        runX++;
        if (runX == 5)
          result += PENALTY_N1;
        else if (runX > 5)
          result++;
      } else {
        finderPenaltyAddHistory(runX, runHistory);
        if (!runColor)
          result += finderPenaltyCountPatterns(runHistory) * PENALTY_N3;
        runColor = module(x, y);
        runX = 1;
      }
    }
    result += finderPenaltyTerminateAndCount(runColor, runX, runHistory) * PENALTY_N3;
  }
  // Adjacent modules in column having same color, and finder-like patterns
  for (int x = 0; x < size; x++) {
    bool runColor = false;
    int runY = 0;
    std::array<int, 7> runHistory = {};
    for (int y = 0; y < size; y++) {
      if (module(x, y) == runColor) {
        runY++;
        if (runY == 5)
          result += PENALTY_N1;
        else if (runY > 5)
          result++;
      } else {
        finderPenaltyAddHistory(runY, runHistory);
        if (!runColor)
          result += finderPenaltyCountPatterns(runHistory) * PENALTY_N3;
        runColor = module(x, y);
        runY = 1;
      }
    }
    result += finderPenaltyTerminateAndCount(runColor, runY, runHistory) * PENALTY_N3;
  }

  // 2*2 blocks of modules having same color
  for (int y = 0; y < size - 1; y++) {
    for (int x = 0; x < size - 1; x++) {
      bool color = module(x, y);
      if (color == module(x + 1, y) && color == module(x, y + 1) && color == module(x + 1, y + 1))
        result += PENALTY_N2;
    }
  }

  // Balance of dark and light modules
  int dark = 0;
  for (const vector<bool> &row : modules) {
    for (bool color : row) {
      if (color)
        dark++;
    }
  }
  int total = size * size;  // Note that size is odd, so dark/total != 1/2
  // Compute the smallest integer k >= 0 such that (45-5k)% <= dark/total <= (55+5k)%
  int k = static_cast<int>((std::abs(dark * 20L - total * 10L) + total - 1) / total) - 1;
  assert(0 <= k && k <= 9);
  result += k * PENALTY_N4;
  assert(0 <= result
         && result
              <= 2568888L);  // Non-tight upper bound based on default values of PENALTY_N1, ..., N4
  return result;
}

vector<int> QrCode::getAlignmentPatternPositions() const {
  if (version == 1)
    return vector<int>();
  else {
    int numAlign = version / 7 + 2;
    int step = (version == 32) ? 26 : (version * 4 + numAlign * 2 + 1) / (numAlign * 2 - 2) * 2;
    vector<int> result;
    for (int i = 0, pos = size - 7; i < numAlign - 1; i++, pos -= step)
      result.insert(result.begin(), pos);
    result.insert(result.begin(), 6);
    return result;
  }
}

int QrCode::getNumRawDataModules(int ver) {
  if (ver < MIN_VERSION || ver > MAX_VERSION)
    throw std::domain_error("Version number out of range");
  int result = (16 * ver + 128) * ver + 64;
  if (ver >= 2) {
    int numAlign = ver / 7 + 2;
    result -= (25 * numAlign - 10) * numAlign - 55;
    if (ver >= 7)
      result -= 36;
  }
  assert(208 <= result && result <= 29648);
  return result;
}

int QrCode::getNumDataCodewords(int ver, Ecc ecl) {
  return getNumRawDataModules(ver) / 8
         - ECC_CODEWORDS_PER_BLOCK[static_cast<int>(ecl)][ver]
             * NUM_ERROR_CORRECTION_BLOCKS[static_cast<int>(ecl)][ver];
}

vector<uint8_t> QrCode::reedSolomonComputeDivisor(int degree) {
  if (degree < 1 || degree > 255)
    throw std::domain_error("Degree out of range");
  // Polynomial coefficients are stored from highest to lowest power, excluding the leading term
  // which is always 1. For example the polynomial x^3 + 255x^2 + 8x + 93 is stored as the uint8
  // array {255, 8, 93}.
  vector<uint8_t> result(static_cast<size_t>(degree));
  result.at(result.size() - 1) = 1;  // Start off with the monomial x^0

  // Compute the product polynomial (x - r^0) * (x - r^1) * (x - r^2) * ... * (x - r^{degree-1}),
  // and drop the highest monomial term which is always 1x^degree.
  // Note that r = 0x02, which is a generator element of this field GF(2^8/0x11D).
  uint8_t root = 1;
  for (int i = 0; i < degree; i++) {
    // Multiply the current product by (x - r^i)
    for (size_t j = 0; j < result.size(); j++) {
      result.at(j) = reedSolomonMultiply(result.at(j), root);
      if (j + 1 < result.size())
        result.at(j) ^= result.at(j + 1);
    }
    root = reedSolomonMultiply(root, 0x02);
  }
  return result;
}

vector<uint8_t> QrCode::reedSolomonComputeRemainder(const vector<uint8_t> &data,
                                                    const vector<uint8_t> &divisor) {
  vector<uint8_t> result(divisor.size());
  for (uint8_t b : data) {  // Polynomial division
    uint8_t factor = b ^ result.at(0);
    result.erase(result.begin());
    result.push_back(0);
    for (size_t i = 0; i < result.size(); i++)
      result.at(i) ^= reedSolomonMultiply(divisor.at(i), factor);
  }
  return result;
}

uint8_t QrCode::reedSolomonMultiply(uint8_t x, uint8_t y) {
  // Russian peasant multiplication
  int z = 0;
  for (int i = 7; i >= 0; i--) {
    z = (z << 1) ^ ((z >> 7) * 0x11D);
    z ^= ((y >> i) & 1) * x;
  }
  assert(z >> 8 == 0);
  return static_cast<uint8_t>(z);
}

int QrCode::finderPenaltyCountPatterns(const std::array<int, 7> &runHistory) const {
  int n = runHistory.at(1);
  assert(n <= size * 3);
  bool core = n > 0 && runHistory.at(2) == n && runHistory.at(3) == n * 3 && runHistory.at(4) == n
              && runHistory.at(5) == n;
  return (core && runHistory.at(0) >= n * 4 && runHistory.at(6) >= n ? 1 : 0)
         + (core && runHistory.at(6) >= n * 4 && runHistory.at(0) >= n ? 1 : 0);
}

int QrCode::finderPenaltyTerminateAndCount(bool currentRunColor, int currentRunLength,
                                           std::array<int, 7> &runHistory) const {
  if (currentRunColor) {  // Terminate dark run
    finderPenaltyAddHistory(currentRunLength, runHistory);
    currentRunLength = 0;
  }
  currentRunLength += size;  // Add light border to final run
  finderPenaltyAddHistory(currentRunLength, runHistory);
  return finderPenaltyCountPatterns(runHistory);
}

void QrCode::finderPenaltyAddHistory(int currentRunLength, std::array<int, 7> &runHistory) const {
  if (runHistory.at(0) == 0)
    currentRunLength += size;  // Add light border to initial run
  std::copy_backward(runHistory.cbegin(), runHistory.cend() - 1, runHistory.end());
  runHistory.at(0) = currentRunLength;
}

bool QrCode::getBit(long x, int i) {
  return ((x >> i) & 1) != 0;
}

/*---- Tables of constants ----*/

const int QrCode::PENALTY_N1 = 3;
const int QrCode::PENALTY_N2 = 3;
const int QrCode::PENALTY_N3 = 40;
const int QrCode::PENALTY_N4 = 10;

const int8_t QrCode::ECC_CODEWORDS_PER_BLOCK[4][41] = {
  // Version: (note that index 0 is for padding, and is set to an illegal value)
  // 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
  // 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40    Error correction level
  {-1, 7,  10, 15, 20, 26, 18, 20, 24, 30, 18, 20, 24, 26, 30, 22, 24, 28, 30, 28, 28,
   28, 28, 30, 30, 26, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30},  // Low
  {-1, 10, 16, 26, 18, 24, 16, 18, 22, 22, 26, 30, 22, 22, 24, 24, 28, 28, 26, 26, 26,
   26, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28},  // Medium
  {-1, 13, 22, 18, 26, 18, 24, 18, 22, 20, 24, 28, 26, 24, 20, 30, 24, 28, 28, 26, 30,
   28, 30, 30, 30, 30, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30},  // Quartile
  {-1, 17, 28, 22, 16, 22, 28, 26, 26, 24, 28, 24, 28, 22, 24, 24, 30, 28, 28, 26, 28,
   30, 24, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30},  // High
};

const int8_t QrCode::NUM_ERROR_CORRECTION_BLOCKS[4][41] = {
  // Version: (note that index 0 is for padding, and is set to an illegal value)
  // 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
  // 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40    Error correction level
  {-1, 1, 1, 1,  1,  1,  2,  2,  2,  2,  4,  4,  4,  4,  4,  6,  6,  6,  6,  7, 8,
   8,  9, 9, 10, 12, 12, 12, 13, 14, 15, 16, 17, 18, 19, 19, 20, 21, 22, 24, 25},  // Low
  {-1, 1,  1,  1,  2,  2,  4,  4,  4,  5,  5,  5,  8,  9,  9,  10, 10, 11, 13, 14, 16,
   17, 17, 18, 20, 21, 23, 25, 26, 28, 29, 31, 33, 35, 37, 38, 40, 43, 45, 47, 49},  // Medium
  {-1, 1,  1,  2,  2,  4,  4,  6,  6,  8,  8,  8,  10, 12, 16, 12, 17, 16, 18, 21, 20,
   23, 23, 25, 27, 29, 34, 34, 35, 38, 40, 43, 45, 48, 51, 53, 56, 59, 62, 65, 68},  // Quartile
  {-1, 1,  1,  2,  4,  4,  4,  5,  6,  8,  8,  11, 11, 16, 16, 18, 16, 19, 21, 25, 25,
   25, 34, 30, 32, 35, 37, 40, 42, 45, 48, 51, 54, 57, 60, 63, 66, 70, 74, 77, 81},  // High
};

data_too_long::data_too_long(const std::string &msg) : std::length_error(msg) {}

/*---- Class BitBuffer ----*/

BitBuffer::BitBuffer() : std::vector<bool>() {}

void BitBuffer::appendBits(std::uint32_t val, int len) {
  if (len < 0 || len > 31 || val >> len != 0)
    throw std::domain_error("Value out of range");
  for (int i = len - 1; i >= 0; i--)  // Append bit by bit
    this->push_back(((val >> i) & 1) != 0);
}

}  // namespace qrcodegen
